IBM OS/390 User Manual

(from ACF/SSP) and user-written VTAM exits. In our example STEPLIB
points to the ACF/SSP library which contains the NCP loader. Any libraries
defined by STEPLIB are PDSs containing load modules, and have similar
DCB characteristics to SYS1.LINKLIB.

4

VTAMLIB contains VTAM tables which are assembled and linked, such as
the subarea Class of Service table and the various mode tables. Again,
VTAMLIB is a load module PDS with DCB=(RECFM=U) and an appropriate
block size. In our example four libraries are concatenated together; the
IBM-supplied VTAM tables are in SYS1.VTAMLIB and any user-defined
replacements are in the two other libraries defined in front of
SYS1.VTAMLIB.

5

VTAMLST contains VTAM tables which are 

not assembled and linked. Here

reside the definitions of the VTAM resources (major nodes), the NCP source
deck, VTAM start options and those tables which VTAM reads in source
form. VTAMLST is a PDS with DCB=(RECFM=FB,LRECL=80) and a
suitable block size. In the example three VTAMLST data sets are
concatenated together; all the VTAM definitions are in these libraries and
SYS1.VTAMLST is not used.

6

The NCPLOAD DD statement points to the data set(s) where NCP load
modules may be found. The DD name for this statement is user-defined,
and VTAM discovers it from the NCP source definitions (BUILD LOADLIB=).

7

In addition, VTAM requires a member IVTPRM00 to be present in the
SYS1.PARMLIB OS/390 data set. This member provides initialization
parameters for Communication Storage Manager (CSM), which is part of
VTAM from V4R4 onwards. CSM provides data storage facilities for both
VTAM and TCP/IP, as part of the high-performance data transfer function
implemented by those products on high-speed connections.

//NET

PROC

PERF=13

//NET

EXEC

PGM=ISTINM01,REGION=6000K,TIME=1440,DPRTY=(15,13),

C

//

PERFORM=&PERF

//STEPLIB DD DSN=SSP.V4R6.SSPLIB,DISP=SHR
//VTAMLIB DD DSN=SA39.VTAMLIB,DISP=SHR
//

DD DSN=ITSC.VTAMLIB,DISP=SHR

//

DD DSN=SYS1.VTAMLIB,DISP=SHR

//

DD DSN=SYS1.NETVIEW.V3R1M0.SCNMLNK1,DISP=SHR

//VTAMLST DD DSN=ITSC.VTAMLST,DISP=SHR
//

DD DSN=BUCZAK.VTAMLST,DISP=SHR

//

DD DSN=RISC.VTAMLST,DISP=SHR

//SISTCLIB DD DSN=SYS1.SISTCLIB,DISP=SHR
//NCPLOAD DD DSN=ITSC.NCPLOAD,DISP=SHR
//

DD DSN=RISC.NCPLOAD,DISP=SHR

Figure 17. VTAM Start Procedure

The differences in the coding of VTAM definitions, tables and start options are
minor, but cannot be ignored. The 

VTAM Resource Definition Reference and the

VTAM Network Implementation Guide should be used to review operating system
differences.

Chapter 9. Telecommunications S u b s y s t e m s